3030 extrusion profile clips

**Updates**:
-Dec 21th 2014: Add a 3rd version of the clip with longer termination that go up to the end of the 30mm extrusion. It can be usefull when 2 sets of cables are going into 2 different extrusion holes.

You will find 2 types of clips here:
-Extrusion_Clip.stl is a simple clip (10mm height) compatible with 3030 extrusion profiles.
-Extrusion_Clip_2.stl is a modified clip with a guide that fit inside the hole of the extrusion profiles. It's also 10mm high.
-Extrusion_Clip_3.stl: is the same as Clip_2 but with additional side length so attempt to clip possible cables on laying on the 2 adjacent sides of the extrusion profile.

The other version with 5mm at the end of the names are for the versions of the clips that are only 5mm high.